In a previous report, we demonstrated that asymptomatic patients with chronic severe aortic regurgitation (AR) and normal left ventricular (LV) systolic function have an excellent prognosis, with less than 4% per year requiring aortic valve replacement because symptoms, LV dysfunction, or both develop. In addition, baseline echocardiographic and radionuclide angiographic measurements were useful in identifying a higher risk subgroup. In that report, we included 79 patients with a mean follow-up period of 4 years, during which 12 patients required operation. We have extended this series to 104 patients followed over a mean 8 year period (range 2-15 years), with 25 events (2 patients died suddenly and 23 underwent operation). At 11 years, 58% of patients remained asymptomatic with normal LV function, an attrition rate less than 4%/year. Many variables describing LV function were associated with outcome, but by multivariate life-table analysis, only age, echocardiographic LV systolic dimension at initial study, and the rate of change in LV systolic dimension and in radionuclide angiographic ejection fraction at rest during serial studies were independently associated with outcome. Thus, within subgroups of patients with chronic AR identified at low or high risk by baseline measurements, further stratification according to risk may be performed on the basis of serial changes in LV systolic function with time. In addition, the LV ejection fraction response to exercise is not helpful to predicting outcome in AR, once age and resting LV function are accounted for.